Internal-external Rotation Research Articles

Compressive force and valgus torque are the predominant applied loads during the pivot shift exam: An in vitro study.

Despite the clinical utility of the pivot shift exam, the requisite applied forces and torques to elicit a pivot shift remain unclear. The purposes of this study are (1) to identify the greatest forces and torques applied to the knee during the pivot shift exam and (2) to evaluate if the applied loads differ among experienced surgeons. Three cadaveric hemipelvis-to-toe specimens (ages 53, 36 and 31 years; two males and one female) with no history of knee or hip injury were utilized. The experimental setup consisted of securing the hemipelvis to a mounting frame via an external fixator to simulate patient positioning during the clinical exam. The hemipelvis, femur, and tibia were spatially tracked by motion capture and the applied loads were measured using a 6-axis force-torque sensor. After sectioning the anterior cruciate ligament (ACL), three board-certified sports medicine surgeons then performed the pivot shift exam on each specimen utilizing their preferred technique. Forces (compression-distraction, anterior-posterior, and medial-lateral) and torques (varus-valgus, internal-external rotation, and flexion-extension) applied to the knee joint immediately preceding the reduction of the proximal lateral tibia during each pivot shift exam were calculated. Compression was the largest applied force averaging 95 N ± 15 N for all surgeons and knees, which was at least 4.5 times greater, on average, than the applied anterior and applied medial tibial forces (p < 0.0001). Valgus was the largest of the three applied torques, averaging 8.5 ± 2.1 Nm. Internal rotation torque was 3.7 times less, on average, than the applied valgus torque (p < 0.0001). Each surgeon applied compressive force. However, anterior force was more variable among surgeons, with one of the three surgeons applying minimal anterior force (p ≤ 0.024). The magnitude of applied torques was similar among examiners (n.s). Compressive force and valgus torque were the predominant applied loads during the pivot shift exam. A lower magnitude of internal rotation torque was also applied. The anterior force was not consistently applied among examiners. These data can better inform clinical, cadaveric, and computational studies utilizing the pivot shift exam to assess knee biomechanics and can be used to educate trainees in conducting this complex manoeuvre. An in vitro biomechanic study.

Role of joint interactions in upper limb joint movements: a disability simulation study using wearable inertial sensors for 3D motion capture

BackgroundRestriction of movement at a joint due to disease or dysfunction can alter the range of motion (ROM) at other joints due to joint interactions. In this paper, we quantify the extent to which joint restrictions impact upper limb joint movements by conducting a disability simulation study that used wearable inertial sensors for three-dimensional (3D) motion capture.MethodsWe employed the Wearable Inertial Sensors for Exergames (WISE) system for assessing the ROM at the shoulder (flexion–extension, abduction–adduction, and internal–external rotation), elbow (flexion–extension), and forearm (pronation-supination). We recruited 20 healthy individuals to first perform instructed shoulder, elbow, and forearm movements without any external restrictions, and then perform the same movements with restriction braces placed to limit movement at the shoulder, elbow, and forearm, separately, to simulate disability. To quantify the extent to which a restriction at a non-instructed joint affected movement at an instructed joint, we computed average percentage reduction in ROM in the restricted versus unrestricted conditions. Moreover, we performed analysis of variance and post hoc Tukey tests (q statistic) to determine the statistical significance (p < 0.05 denoted using *) of the differences in ROM of an instructed joint in the unrestricted versus restricted conditions.ResultsRestricting movement at the shoulder led to a large reduction in the average ROM for elbow flexion–extension (21.93%, q = 9.34*) and restricting elbow movement significantly reduced the average ROM for shoulder flexion–extension (17.77%, q = 8.05*), shoulder abduction–adduction (19.80%, q = 7.60*), and forearm pronation-supination (14.04%, q = 4.96*). Finally, restricting the forearm significantly reduced the average ROM for shoulder internal–external rotation (16.71%, q = 3.81*) and elbow flexion–extension (10.01%, q = 4.27*).ConclusionsJoint interactions across non-instructed joints can reduce the ROM of instructed movements. Assessment of ROM in the real-world using 3D motion capture, for example using the WISE system, can aid in understanding movement limitations, informing interventions, and monitoring progress with rehabilitation.

The effect of knee braces on knee joint kinematics at different exercise speeds

ABSTRACT This study aims to investigate the influence of a new semi-rigid knee joint braces on kinematics using the Opti-knee knee joint kinematic analysis system at various exercise speeds. Twenty-four healthy young male adults were recruited for this study. Participants were randomly assessed while wearing and not wearing knee brace at four different speeds on a treadmill: normal walking (3.6 km/h), brisk walking (5.4 km/h), jogging (9 km/h), and moderate intensity running (10.8 km/h). Six degrees of freedom kinematic data from the knee joint were collected. Paired t-tests were conducted to calculate the kinematic differences. At speeds of 3.6 km/h and 5.4 km/h, wearing the knee brace led to reduced knee joint mobility in anterior-posterior translation, superior-inferior translation, internal-external rotation, and flexion-extension angles during the stance phase (P < 0.05). At 9 km/h, wearing the brace reduced knee joint internal-external rotation and flexion-extension mobility during the stance phase (P < 0.05). At 10.8 km/h, wearing the brace reduced knee joint flexion-extension mobility during the stance phase (P < 0.05). Wearing brace has significant influence on knee kinematics at four speeds, and the effect of brace varies with the speed of movement.

Evaluation of a novel robotic testing method for stability and kinematics of total knee arthroplasty.

This work developed a novel preclinical test of total knee replacements (TKRs) in order to explain TKR instability linked to patient dissatisfaction. It was hypothesized that stability tests on the isolated moving prostheses would provide novel comparative data on the stability and kinematics among TKR designs. Three TKR designs, DePuy Synthes Attune MS, Stryker Triathlon and Zimmer Biomet Persona MC, were assessed using a robotic arm while flexing-extending 0-140°. Tests imposed 710 N body weight combined with three tibial loads: no anterior-posterior (AP) force, 90 N anterior or 90 N posterior force. Other load effects were minimized and the kinematics was recorded. Each implant was tested six times to investigate the repeatability of the method. Data were analysed using statistical parametric mapping with one-way analysis of variance (ANOVA). If significance was found (p < 0.05), post hoc t tests with Bonferroni correction were used to contrast groups. Significant differences were found throughout flexion-extension. Femoral rollback, AP stability, coupled internal-external rotation and AP position (roll-back) were all influenced by implant design. AP stability of the TKRs reduced with flexion reaching Attune 15 mm, Persona 13 mm and Triathlon 21 mm at 140° flexion. Tractive rolling significantly affected kinematics in the less congruent Triathlon design, with 6 mm different paths between flexion and extension motion (p < 0.05 across 5-100°). Paradoxical anterior femoral sliding in early flexion (0-40°) occurred in Persona and Triathlon designs. The novel testing technique provides, for the first time, comparative data on the inherent stability and kinematics of the TKR implants themselves across the arc of flexion-extension, independent of variables including soft tissue behaviour and surgical technique. The data show how much each prosthesis can contribute to the stability and motion of the implanted knee. Similar data from a wider range of designs will enable more informed decisions regarding implant design choice, aiming to reduce the prevalence of TKR instability in patients. Controlled laboratory study.

The Effect of Isometric Exercise Position on the Effectiveness of Isolated Work of the Thigh Flexor Muscles Based on the Results of the sEMG Study.

The main function of the hamstring muscles is to bend the knee joint and support the function of the hip extensors. Their frequent injuries are the result of overload related to, among others, dynamic running or jumping, and inadequate preparation for athletics activities. The asymmetry of the work of individual flexor muscle groups is clearly marked in the case of valgus or varus of the knee joint, i.e., in different positions of the lower limb. The aim of the study was to determine the position and form of a rehabilitation exercise in which an isolated group of muscles flexing the knee joint will show the greatest bioelectrical activity. The study involved 25 students of the Jagiellonian University Medical College. The students were aged 20-26. The average age was 22.9 (±1.4). The study participants included 17 women with an average age of 23.0 (±1.1) and 8 men with an average age of 22.6 (±1.9). Women constituted 68% and men 32% of all respondents. All participants agreed to participate in the study. Surface electromyography measurements in both lower limbs provided an initial number of 50 cases. The activity of the knee flexor muscles during isometric contraction with resistance was measured in correlation with three foot and lower leg settings: internal rotation, neutral position, and external rotation. The bioelectrical activity of the semitendinosus muscle is significantly higher (p < 0.01) in the internal rotation position than in the neutral position of the lower leg, while the bioelectrical activity of the biceps femoris muscle is inversely higher (p < 0.01) in the external rotation position than in the neutral position. The results are significant for both average and maximum values of muscle stimulation. During isometric contraction with resistance, the semitendinosus muscle shows the greatest bioelectrical activity in the internal rotation position of the lower leg and foot, and the biceps femoris muscle in the external rotation position of the lower leg and foot. The above information has important implicational applications when improving isolated groups of hamstrings. In the future, this may contribute to more effective rehabilitation of patients with injuries of the muscles described in the article.

Does cranial cruciate ligament repair by tibial plateau leveling osteotomy surgery restore dog’s natural kinematics? – A case series

Tibial plateau leveling osteotomy (TPLO) serves as an effective method of functional stabilization for treating cranial cruciate ligament (CrCL) deficiency. It is not clear if TPLO could restore the natural kinematics of the stifle, hip, and tarsal joints of the affected limb during walking. The hind limb motion between TPLO cases and control groups in eight adult dogs (4 French Bulldogs and 4 Pit Bull Terrier) was recorded by a motion capture system. Three-dimensional (3D) angular motions of the hip, stifle, and tarsal joints—including flexion-extension, abduction-adduction, and rotations—were computed and compared. Significant differences in joint kinematics were observed between TPLO cases and controls. In Case 1, the TPLO case in the French Bulldog showed differences in hip, stifle, and tarsal flexion-extension, abduction-adduction, and internal-external rotation. Asymmetries between affected and unaffected limbs were also detected in hip and stifle motions (up to 43° in some cases). Similar patterns of differences were found in Pit Bull Terriers Case 2 and Case 3, with significant variations in hip, stifle, and tarsal movements. Case 3 did not show hip asymmetries, but notable stifle and tarsal asymmetries were observed. The general daily activity performance for French Bulldogs and Pit Bull Terriers that underwent TPLO procedures was positive. The general daily restricted activity performance for the French Bulldog and Pit Bull Terriers that underwent TPLO procedures was positive. Our findings suggested that natural hind limb kinematics during gait was not restored in TPLO hind limb cases in both breeds.

A retrospective comparative study on the effectiveness of multisite injection versus arthroscopic capsular release for idiopathic frozen shoulder

Arthroscopic capsular release is a most well-known technique with favorable outcomes for frozen shoulder. However, considering the surgical trauma and the improvement of multisite injection, we design a study to compare the pain relief and safety of multisite injection (MI) versus arthroscopic capsular release (ACR) for frozen shoulder. A total of 80 patients with unilater al frozen shoulder were enrolled in this study. Group RBT (n = 40) received multisite injection (0.5% lidocaine and triamcinolone acetonide, once a week, no more than 2 injections), while Group ACR received arthroscopic capsular release. The following parameters were employed to compare: visual analog scale (VAS), range of motion (ROM), the Disability of Arm, Hand, and Shoulder (DASH) score and Oxford shoulder score (OSS). Side effects were also recorded. The VAS, ROM, DASH and OSS all improved significantly (P < 0.001). Internal rotation and external rotation at 1 month after operation were better in ACR group (40.35 ± 4.79 Vs 36.58 ± 7.49, 40.55 ± 4.37 Vs 38.63 ± 4.01, P = 0.009,0.043). However, no significance in terms of functional results and ROM was found at 6 months after operation. The OSS, DASH and VAS in patients with diabetes were 44.25 ± 3.05, 2.29 ± 1.12 and 0.50 ± 0.72, compared with 43.89 ± 3.09, 2.34 ± 1.49 and 0.29 ± 0.56 in patients without diabetes (P = 0.636, 0.889, 0.157). Multisite injection and arthroscopic capsular release are both effective treatments in the treatment of frozen shoulder. However, multisite injection is a simple, cost effective and superior alternative.

Accuracy and precision of Volumetric Matching Micromotion Analysis (V3MA) is similar to RSA for tibial component migration in TKA.

Radiostereometric analysis (RSA) is the current gold standard to determine implant migration, but it requires bone markers and special equipment. Therefore, we developed VoluMetric Matching Micromotion Analysis (V3MA), a software program for Computed Tomography-based radiostereometric analysis (CT-RSA). This study aimed to determine the accuracy and precision of V3MA in vitro compared to RSA and provide a clinical proof of concept. The accuracy (RMSE (Root Mean Squared Error)) and precision (SD (standard deviation)) of V3MA were compared to RSA. A tibial component was placed in 21 different positions within a cadaveric bone to assess accuracy. For precision,a total of 20 repeated zero-migration examinations from 4 cadaveric bones with cemented tibial components were performed. In 6 total knee arthroplasty (TKA) patients 1 to 5 year migration was measured with V3MA and RSA. V3MA accuracy ranged between 0.02 and 0.09 mm for translations and was 0.01° for internal-external rotations. For RSA, the accuracy ranged between 0.03 and 0.09 mm for translations and was 0.09° for internal-external rotations. V3MA precision ranged between 0.01 and 0.06 mm for translations and 0.02 to 0.07° for rotations. RSA precision ranged between 0.00 and 0.06 mm for translations and 0.04 to 0.25° for rotations. V3MA was successful in 6 clinical cases and no systematic bias was present. In conclusion, the accuracy and precision of V3MA were similar to RSA. Therefore, V3MA is a promising alternative to RSA in migration measurements of tibial components in TKA.

Novel arthrometer for quantitative clinical examination of the knee in three planes: Safety, reliability, minimum detectable changes, and side-to-side differences in healthy subjects

Physical examination of the knee joint is used to diagnose the type and severity of knee ligament injury; however, these exams are qualitative and subjective. To perform common physical examinations, we developed an arthrometer which quantitatively measures the load–displacement response in anterior-posterior (AP) translation, internal-external rotation (IER) and varus-valgus (VV) rotation. Here we describe safety, reliability, minimum detectable changes (MDCs), and absolute side-to-side differences in twenty young, healthy subjects (ten male, ten female, mean age: 28 ± 6 years). The arthrometer consists of an instrumented mechanical linkage, a force-moment sensor, and software for real-time visualization and recording of the load–displacement responses. During testing, the subject sits reclined in a chair with their knee fixed at 30° of flexion. Two examiners tested both knees of each subject twice to assess reliability via intraclass correlation coefficients (ICC). All subjects completed the test protocol with minimal pain and stated that they would volunteer to be tested again. Each knee required on average five minutes to test. All intra-test reliabilities were excellent (≥0.91). Intra-examiner reliabilities ranged from good to excellent (0.62–0.89), and inter-examiner reliabilities were good to excellent (≥0.72). MDCs for repeat measures were ≤ 4.5 mm, 4.6°, and 2.3° for AP, IER, and VV, respectively. The absolute side-to-side differences for this cohort averaged 3.8 mm in AP, 5.5° in IER, and 2.2° in VV. Our arthrometer was safe, testing was time-efficient, and MDCs in our cohort of healthy subjects support utilization of this device for clinical research.

An Insert Goniometer Can Help Select the Optimal Insert Thickness When Performing Kinematically Aligned Total Knee Arthroplasty with a Medial 1:1 Ball-in-Socket and Lateral Flat Surface Insert and Posterior Cruciate Ligament Retention.

Current surgical practices in total knee arthroplasty (TKA) have advanced and include significant changes and improvements in alignment philosophies, femorotibial implant conformities, and ligament management to replicate in vivo knee kinematics. While corrective measures have emphasized sagittal plane alignment to restore normal flexion-extension (F-E) motion and coronal plane ligament balance, internal-external (I-E) rotation kinematics in the axial plane have been largely neglected. Recent in vivo evidence indicates that the combination of factors necessary to closely restore native tibial rotation as the knee flexes and extends is kinematic alignment (KA), which resurfaces the patient's pre-arthritic knee without releasing ligaments, an insert with medial 1:1 ball-in-socket conformity and a lateral flat surface, and posterior cruciate ligament (PCL) retention. However, the inherent anterior-posterior (A-P) stability provided by the medial 1:1 ball-in-socket limits the surgeon's ability to select the correct insert thickness using manual laxity testing. Accordingly, this review presents the design and validation of an instrument called an insert goniometer that measures I-E tibial rotation for inserts that differ in thickness by 1 mm and uses rotation limits at extension and 90° flexion to select the optimal insert thickness. The optimal thickness is the one that provides the greatest external tibial orientation in extension and internal tibial orientation at 90° flexion without lift-off of the insert.

Isokinetic Strength and Balance Analyses for Predicting Return to Sports After the Latarjet Procedure: A Prospective Cross-sectional Study

Background: Isokinetic torque in shoulder internal rotation (IR) and external rotation (ER) can be considered as potential indicators for dynamic stability of the glenohumeral joint. Purpose: To assess the efficacy of 4-month isokinetic testing in predicting the 6-month return-to-sports (RTS) status after Latarjet surgery, explore its correlations with testing parameters, and identify optimal thresholds to ensure a safe RTS. Study Design: Cohort study; Level of evidence, 2. Methods: The study assessed athletes who underwent the Latarjet stabilization procedure between January 2022 and June 2023. The primary outcome was RTS at 6 months after surgery. The primary examined predictors were isokinetic testing metrics at 4 months postoperatively. Secondary outcomes comprised the modified Closed Kinetic Chain Upper Extremity Stability Test (mCKCUEST) and several patient-reported outcome measures, including the Walch-Duplay score, the Western Ontario Shoulder Instability Index (WOSI), and the Shoulder Instability–Return to Sports after Injury scale. To assess the predictors, patients were divided into those who returned to any level of sports compared with those who did not return to sports. The correlation between isokinetic testing results and other outcome scores was also analyzed. Results: A total of 71 patients (mean age, 27.43 ± 9.09 years) were included in the study. Of these, 23.61% did not return to sports, 38.89% returned at a lower level, and 37.50% returned to the same level. Significant rotational strength disparities were noted. Patients who did not return to sports at 6 months demonstrated inferior strength in concentric ER at 60 deg/s, concentric ER at 240 deg/s, concentric IR at 240 deg/s, and eccentric IR at 30 deg/s (P < .05). Similar trends appeared for all studied patient-reported outcome measures and the mCKCUEST (P < .05). Receiver operating characteristic analysis emphasized the significance of isokinetic testing in concentric ER at 240 deg/s (area under the curve = 0.759; P = .001; cutoff = 0.32 N·m/kg; sensitivity = 100.0%; specificity = 49.1%) and eccentric ER at 30 deg/s (area under the curve = 0.760; P = .001; cutoff = 0.51 N·m/kg; sensitivity = 94.1%; specificity = 49.1%) for RTS prediction. Additionally, ER strength moderately correlated with the Walch-Duplay score across all examined velocities (r = 0.26-0.34; P < .05). The modified WOSI score was weakly linked to ER strength at 240 deg/s and 30 deg/s (r = 0.24-0.25; P < .05) as well as moderately linked to the limb symmetry index in ER at 60 deg/s and 30 deg/s (r = 0.30-0.38; P < .05). Conclusion: Isokinetic testing can act as an independent predictor of successful RTS after Latarjet surgery, with concentric ER at 240 deg/s, concentric IR at 240 deg/s, eccentric ER at 30 deg/s, and eccentric IR at 30 deg/s showing the most accuracy. Strength recovery in ER was associated with better Walch-Duplay and modified WOSI scores.

Addressing Extra-Articular Impingement in the Athlete

Extra-articular impingement (EAI) is an atypical, infrequent source of hip pain. Unlike femoroacetabular impingement (FAI) and acetabular dysplasia (AD), EAI results from abnormal contact of the proximal femur and trochanteric region, and the ischium or subspine areas. Hip pain and potential instability are reported. Causes of EAI include a narrowed ischiofemoral space, coxa valga, femoral torsion abnormalities, avulsion malunions, and more complex deformities resulting from pediatric hip diseases. Unique history and examination findings not commonly seen with standard FAI are noted, including pain with standing and hip extension and imbalanced hip motion with excessive internal rotation and limited external rotation (or vice versa). Surgical indications are yet to be definitively defined, but surgical treatment options include lesser trochanter resection, femoral osteotomy, and surgical hip dislocation. Proper workup and surgical planning have demonstrated good outcomes for treatment of EAI with these techniques, but information to optimally define which patients benefit most from which surgeries is pending.

The Effects of the Leg Position on the Nordic Hamstring Exercise Eccentric Force: A Randomized Cross-Over Study

Given the posterior chain configuration, it is anticipated that tibial positioning influences hamstring recruitment; medial hamstrings should be more activated during medial rotation, while lateral hamstrings should be more activated during lateral rotation. However, most studies showing this pattern have focused on concentric or isometric strength, leaving the influence on eccentric strength fairly unknown. Therefore, the aim of this study was to investigate the electromyographic response of the hamstring muscles during Nordic hamstring exercises in three leg positions: internal rotation, external rotation, and neutral. This study encompassed a randomized crossover study and used surface electromyography to analyze the activity of the biceps femoris and semitendinosus muscles during the Nordic hamstring exercise, in the three positions. Results indicated no statistically significant differences in muscle activation between positions or sides (p &gt; 0.05), though small effect sizes were observed for the biceps femoris in different positions (η2 = 0.01–0.03). Furthermore, the internal rotation position generally elicited the highest muscle activations. Notably, biceps femoris muscles exhibited higher activations compared to semitendinosus muscles, with the greatest differences seen in the internal rotation position. This suggests that tibial rotation influences hamstring recruitment patterns; however, it was lower than expected.

Impact of tendon transfer on scapulothoracic and glenohumeral motion in children with brachial plexus birth injuries

BackgroundTendon transfers are often utilized to improve shoulder external rotation and abduction in children with brachial plexus birth injuries and are designed to improve glenohumeral (GH) joint motion. However, changes in scapulothoracic (ST) and glenohumeral (GH) joint function after tendon transfer are not well defined. The purpose of this study was to quantify changes in GH, ST, and humerothoracic (HT) joint function before and after tendon transfer, and we hypothesized that tendon transfers would reorient the arc of motion into more external rotation and abduction, but not increase GH motion. MethodsMotion analysis was performed in 15 children (ages 3-16) before and after transfer of teres major and/or latissimus dorsi. Scapulothoracic, GH, and HT joint angles were measured in a neutral, resting position and each of the modified Mallet positions. Joint angular displacements from the neutral position and the total arc of internal-external rotation for each joint were also calculated. Relevant joint angles, joint angular displacements, and internal-external rotation arcs were compared using multivariate analyses of variance with repeated measures and univariate post-hoc analyses. ResultsGlenohumeral and HT external rotation were significantly increased in all positions postoperatively. The arc of GH internal-external rotation was unchanged, but oriented in more external rotation after surgery. Only 6 patients gained active external rotation. Glenohumeral and HT internal rotation were significantly decreased after surgery, but ST internal rotation was significantly increased. Two patients had loss of midline function. In the abduction position, GH elevation joint angles were unchanged, but ST and HT elevation increased. DiscussionOnly four patients gained active GH external rotation and maintained their internal rotation. Each of those patients underwent isolated tendon transfer without concomitant joint release. Seven patients maintained their preoperative internal rotation, which was attributed to increased ST internal rotation. The other half of patients lost internal rotation and gained external rotation through reorientation of the arc of rotation. Nine patients gained HT elevation, with three attributed to increased ST upward rotation, five attributed to a combination of increased ST upward rotation and increased GH elevation, and one attributed to increased GH abduction contracture. These findings challenge the dogma that teres major/latissimus dorsi tendon transfers augment GH motion and highlight the importance of ST function for outcome determination.

Isokinetic Peak Torque Improvement and Shoulder Muscle Ratios Imbalance Correction After Specific Strength Training on a New Ballistic Throwing Device: A Randomized Controlled Trial.

The aim of this study was to investigate the effects of 8-week ballistic-strength-training program using a validated specific throwing device (ie,Arm/Shoulder Specific Strength Device), on isokinetic shoulders' rotation muscle-torques and ratios as well as range of motion in team handball players. A repeated-measures experimental design with a randomized controlled trial was used. Twenty-six high-level competitive male U-19 team handball players were randomly assigned into training (TG, n = 15) and control (n = 11) groups. The TG undertook a twice a week for 8-week periodized throws program with an individually predetermined optimal load. The program incorporated shackled eccentric and concentric exercises using the Arm/Shoulder Specific Strength Device. Peak torques, functional, and conventional ratios for both arms at different angular velocities (60°·s-1, 180°·s-1, and 300°·s-1) were assessed over time and between groups, using an isokinetic dynamometer. A significant improvement for TG (P < .01; d = 1.13 [moderate]; +20.2%) of the concentric peak torques for dominant arm in external rotation was observed at 300°·s-1. Significant (P < .05-.01) increases were also noted for nondominant arm at the 3 studied angular velocities. In addition, 300°·s-1 eccentric peak torques of the dominant arm and nondominant arm have significantly improved for both external and internal rotations (P < .05; d = .99 [moderate] and d = 1.21 [large]; +15.7% and + 17.9%, respectively) with small changes at the other angular assessed velocities. Posttraining, TG's dominant arm showed significant improvements (P < .05-.01) in functional and conventional ratios at all velocities. Notably, significant differences (P < .05-.01) were observed at 60°·s-1 and across all velocities when comparing the TG with the control group. TG showed significant increase for internal rotation and external rotation shoulder range of motions (P < .05; d = 1.22-1.27 [large]), +5.0% and +7.7%, respectively). The specific 8-week throwing training program on the Arm/Shoulder Specific Strength Device showed significant performance improvements in almost all assessed isokinetic concentric and eccentric peak torques as well as internal and external range of motion increase for both arms while ensuring rotator cuff torque ratios and shoulder mobility in team handball real sport-specific condition.

Shoulder Rotation Affects Trapezius Muscle Activity During Shoulder Horizontal Abduction.

Shoulder horizontal abduction exercise in the prone position is effective for strengthening the lower trapezius muscle. However, this exercise is difficult for patients with acute pain or those undergoing initial rehabilitation because of the postural characteristics of the exercise. This study aimed to (1) investigate the effect of a shoulder horizontal abduction exercise when performed with a different amount of shoulder rotation on the trapezius muscle activation and scapular anterior/posterior tilt angle and (2) evaluate the effect of shoulder rotation on the acromiohumeral distance while sitting. Fifteen healthy men performed shoulder horizontal abduction exercise in three shoulder positions (internal rotation, neutral rotation, and external rotation). During exercises, we measured trapezius muscle activity using an electromyography system and scapular anterior/posterior tilt angle using an inclinometer application. We also measured the acromiohumeral distance using real-time ultrasonography before the exercises. Increases in lower trapezius and middle trapezius muscle activities and a decrease in scapular anterior tilt occurred in shoulder external rotation compared with other positions (p<0.001). Shoulder external rotation also significantly increased acromiohumeral distance in the sitting position (p<0.05). We propose that shoulder external rotation effectively and safely increases middle and lower trapezius muscle activities during the sitting shoulder horizontal abduction exercise.

Isometric Shoulder and Hip Strength Impact on Throwing Velocity and Reactive Strength.

The aim of the study is to examine relationships between shoulder extension-flexion and internal-external rotation strength of professional male handball players with throwing velocity, and the hip extension-flexion strength with horizontal and vertical reactive strength index. Fifteen professional male handball players participating in 1st League matches took part in the study. The results showed that isometric shoulder flexion and extension strength significantly predicted stable throwing velocity (r2=between 0.27-0.73) and dynamic throwing velocity (r2=between 0.30-0.62). In addition, isometric internal and external rotation strength significantly predicted stable throwing velocity (r2=between 0.32-0.54) and dynamic throwing velocity (r2=between 0.31-0.44). Moreover, isometric hip extension and flexion strength significantly predicted vertical reactive strength index (r2=between 0.31-0.45) and horizontal reactive strength index (r2=between 0.26-0.42). In conclusion, it was observed that shoulder strength has an enhancing effect on handball players' throwing velocity, while hip strength is a determining factor for the reactive strength index. In this context, it is assumed that shoulder weakness during throwing will affect the accuracy and velocity of throwing by disrupting the angular momentum, while weakness in the hip during the jump phase of the throwing motion will negatively affect the explosive power by limiting stabilization during landing.

Magnetic resonance arthrography with positional manoeuvre for the diagnosis of synovial fold of posterior shoulder joint capsule.

The objective of this study is to prospectively assess the effectiveness of shoulder magnetic resonance (MR) arthrograms with positional manoeuvres in detecting posterior synovial folds. Two radiologists independently assessed all axial MR arthrograms in internal rotation, neutral position, and external rotation for the presence of a posterior synovial fold. The diagnostic performances of the MR arthrograms were then compared, with results validated through arthroscopy. Arthroscopy was performed on 81 of the 150 patients included in the study. A posterior synovial fold was identified arthroscopically in eleven of these patients. Measurements of the posterior synovial fold obtained in external rotation and the neutral position of the arm showed a significant correlation with arthroscopic results (p < 0.05). For detecting the posterior synovial fold with arthroscopic correlation, the sensitivity and specificity values for observer 1 and observer 2 were 100-81.4% and 100-88.6%, respectively, for MR arthrograms in the neutral position; 100-52.9% and 100-62.9% for MR arthrograms in external rotation; and 100-95.7% and 81.8-98.6% for MR arthrograms in internal rotation. There was a fair agreement for MR arthrography in external rotation for detecting posterior synovial folds, while MR arthrograms in internal rotation and neutral position showed near-perfect and significant interobserver agreement. The rotational positions of the humeral neck during MR arthrographic examination can influence the diagnostic specificity and sensitivity of axial MR arthrograms in detecting the posterior synovial fold. The posterior synovial fold can mimic a posterior labral detachment. Therefore, its correct identification is crucial in order to avoid unnecessary surgical procedures. Movement of the shoulder may introduce variability in MR arthrography appearance. Rotation of the humeral neck during MR arthrography can affect diagnoses in posterior synovial fold detection. Given that posterior synovial folds can imitate posterior labral detachment, their correct identification is crucial to avoid unnecessary surgical procedures.

Reliability and validity of belt-stabilized and tension dynamometry for assessing hip strength and power in uninjured adults

ObjectivesTo investigate the intra-rater reliability and validity of belt-stabilized and tension dynamometry to assess hip muscle strength and power. DesignRepeated measures. SettingBiomechanics laboratory. ParticipantsSeventeen uninjured adults (age = 22.0 ± 2.3y; 13 females). Main outcomes measuresPeak torque (strength) and rate of torque development (RTD; power) were measured for hip abduction, internal rotation, external rotation and extension using an isokinetic dynamometer, and belt-stabilized and tension dynamometry. ResultsFor peak torque assessment, belt-stabilized and tension dynamometry showed good (Intraclass Correlation Coefficient [ICC] = 0.848–0.899) and good-to-excellent (ICC = 0.848–0.942) reliability, respectively. For RTD, belt-stabilized dynamometry showed fair reliability for abduction (ICC = 0.524) and good reliability for hip internal rotation, external rotation, and extension (ICC = 0.702–0.899). Tension dynamometry showed good reliability for all motions when measuring RTD (ICC = 0.737–0.897). Compared to isokinetic dynamometry, belt-stabilized and tension dynamometry showed good-to-excellent correlations for peak torque assessment (r = 0.503–0.870), and fair-to-good correlations for RTD (r = 0.438–0.674). Bland-Altman analysis showed that measures from belt-stabilized and tension dynamometry had clinically meaningful disagreement with isokinetic dynamometry. ConclusionTension dynamometry is reliable for assessing hip strength and power in all assessed motions. Belt-stabilized dynamometry is reliable for assessing internal rotation, external rotation, and extension. Validity of both methods is questionable, considering the lack of agreement with isokinetic dynamometry.

Standardization and Reproducibility of Dynamic Stress Testing for Occult Pelvic Ring Instability.

Examination under anesthesia (EUA) (stress fluoroscopy) is commonly done after pelvic ring injury to identify occult instability because unstable disruptions may displace causing morbidity. The force applied during EUA for these injuries has not been standardized. The purpose of this study was to examine the forces used during the EUA by experienced orthopaedic trauma pelvic surgeons. Orthopaedic traumatologists performed simulated EUA on a cadaver at two North American pelvis and acetabular courses using internal rotation (IR), external rotation, and push-pull maneuvers while wearing a handheld dynamometer to measure force. All surgeons used a comparable method, and each performed EUA multiple times. Maximum forces were measured in Newton (N). Eighteen surgeons participated. Four had been practicing for <5 years, six for 5 to 10 years, six for 11 to 20 years, and two for >20 years. Surgeons applied a force ranging from 40.4 to 374.9 N during IR, 72.9 to 338.4 N during external rotation, and 25 to 323 N during push-pull, with notable variability seen between surgeons. Three surgeons (18%) had >50-N variability on serial trials of a single EUA maneuver (IR). This is the first study evaluating the forces applied during pelvic EUA used to assess ring stability. Notable variability existed among surgeons performing EUA and in serial examinations by the same surgeon. Additional study is needed to standardize the displacement measured and threshold for instability that guides management.